Bent-core lc decorated gold nanoclusters

ABSTRACT

Novel thiol-terminated bent-core liquid crystals (LCs) are used to decorate gold nanoparticles. Thioacetate or xanthate/xanthogenate functional groups are used to effect the attachment of the LCs to the gold nanoparticles. Such bent-core decorated nanoparticles may be dissolved in bent-core liquid crystal host media to provide polarizable systems which respond quickly to applied electric fields and exhibit other interesting and useful optical and electro-optic behaviour.

FIELD OF THE INVENTION

This invention relates to the preparation of novel bent-core liquidcrystals (LCs) having mesomorphic properties and to the use of bent-coreLCs to prepare bent-core LC decorated gold nanoparticles [NPs]. NPs havebeen used to prepare nanoclusters by evaporation from solution or bydispersion of capped gold NPs in a bent-core liquid crystal medium. Suchnanoclusters exhibit useful electronic, optical and/or photonicapplications.

BACKGROUND OF THE INVENTION

The development of nanoparticles (NPs) covered with organic functionalgroups has recently excited considerable interest in liquid crystal (LC)nanoscience. Research over the past few years has shown that thepresence of NPs dispersed into low molecular mass thermotropic LCs canbring about striking changes to the optical and electro-optic behaviourof LC systems. For example, it has been demonstrated that doping nematicLCs with nanoscale MgO can result in lower operating voltages andshorter response times. Gold nanoparticles in particular have been shownto allow electrically controlled light-scattering when embedded in anematic LC, allowing for voltage-dependent colour tuning.

In addition, liquid crystalline phases having one or two-dimensionallong range orientational ordering also present an excellent choice forthe synthesis as well as assembly of NPs into larger, organizedstructures (arrays) with the added benefit of fluidity imparted by theLC. Hence, the final self-assembled superstructure can be manipulated byexternal stimuli, a quality not shared by many products of otherassembling methods using polymers or surfaces (interfaces) leading tomore confined NP arrays.

Thus far, the majority of studies have concentrated on lyotropic liquidcrystalline systems as templates or matrices for the patterning of NPs.In addition, most studies involving the effect of NPs on the LC hostitself have focused on conventional rod-like LCs.

We have extended such studies to the class of thermotropic liquidcrystalline compounds which have come to be known as bent-core or“banana-shaped” LCs. Bent-core compounds exhibit unique properties (forexample, high polarization values and second-order susceptabilitycoefficients) which recommend them for use in pyroelectric orpiezoelectric applications in non-linear optical (NLO) devices or indispersive devices similar to polymer-dispersed liquid crystals (PDLCs).

SUMMARY OF THE INVENTION

There are a number of aspects to the present invention, a way of makingthiol-terminated bent-core liquid crystals, using these to decoratemetal (Au) nanostructures (in particular, nanoparticles) and the use andsytheses of thioacctate and xanthate functional groups to bring aboutattachment to gold nanoparticles. Bent-core decorated nanoparticlesaccording to the invention have been found to be reasonably soluble inbent-core liquid crystal hosts, affording LC systems with desirableelectroco-optical properties, in particular a more rapid switching timestemming from rapid polarization of the LC in response to an appliedelectric field.

According to a first aspect of the invention, novel thiol-,thioacetate-, and xanthate-terminated bent-core LC compounds have beenprepared. These have been shown to have useful mesomorphic properties.The thiol-terminated bent-core compounds have been successfully attachedto gold nanoparticles, which display self-assembly behavior out ofsolution.

According to a further aspect of the invention, there is provided amethod for preparing bent-core liquid crystal decorated goldnanoclusters by agitating a solution of gold nanoparticles with abent-core liquid crystal compound in a suitable solvent, slowlyevaporating the solvent and drying the mixture.

According to a futher aspect of the invention, there is provided amethod for preparing bent-core liquid crystal decorated goldnanoclusters by using bent-core LCs as monolayer capping agents directlybound to the NP surface and dispersing the capped gold nanoparticles ina bent-core liquid crystal host medium to promote the self-assembly ofbent-core liquid crystal decorated gold nanoclusters into arrays.

According to a still further aspect of the invention, there is provideda method for enhancing spontaneous polarization in an SmCPA bydispersing therein bent-core decorated liquid gold nanoclusters.

DESCRIPTION OF THE DRAWINGS

The invention will now be described, first in broad general terms, thenby way of a number of specific examples in connection with the attacheddrawings, in which

FIG. 1 is schematic representation of the use of thiol-terminatedbent-core compounds in assisting the formation of gold nanoparticlearrays (upper section of drawing) and the use of such nanoclusters indispersions with bent-core LC hosts potentially altering their thermalproperties and/or their electro-optic response (lower section).

FIG. 2 shows enlarged views, through crossed polarizers, of the texturesof the columnar phases obtained, upon cooling from the isotropic liquidphase, for (a) BC12 at 74° C. and (b) BC16 at 78° C.

FIG. 3 presents six polarized optical micrographs of one of the novelbent-core compounds (BC10) prepared by the invention, followingdiffering cooling and testing treatments.

FIG. 4 represents differential scanning calorimetry (DSC) traces of BC10showing the meta-stable LC phase on cooling between 86° C. and 83° C.Both heating and cooling runs were measured at 10° C. min⁻¹.

FIG. 5 comprises copies of high-resolution TEM images of the goldnanoclusters Au1 and Au2 referred to in the present description.

FIG. 6 shows thin film sections of suspensions of differentconcentrations (wt %) of Au1 in BC8 forming a Col_(r) phase (left) andin BC1 forming a SmCP_(A) phase (right) at room temperature after onethermal cycle through the LC phase formed on cooling. The colour(wavelength of the surface plasmon resonance, SPR band) observed for thetwo sets is distinctly different from one series to the other, butconsistent within each series.

FIG. 7 is a graphic illustration of the shift of the SPR band arisingfrom the change of bent-core host in UV-vis spectra of thin filmsuspensions of 10 weight percent Au1 in BC1 and BC8, both at 90° C. oncooling from the isotropic liquid phase (both LC hosts in theirrespective LC phases).

FIG. 8 comprises two photomicrographs showing textures of the SmCPa ofthe synthesized bent-core derivative BC1 at 0V and at +100V.

FIG. 9 presents photomicrographs showing the textures of the SmCP_(A)phase of BC1 doped with 5 weight percent of Au1 at V_(pp)=200 V.

FIG. 10 presents three graphical representations of current response toa triangular voltage in the SmCP_(A) phase of (a) pure BC1; (b) BC1doped with 2.5 weight percent Au1; and (c) BC1 doped with 5 weightpercent Au2.

FIG. 11 is a polarized optical photomicrograph of the texture formed by5 weight percent Au1 in BC1 on cooling at the transition from theisotropic liquid to the SmCP_(A) phase (100×).

FIGS. 12A and 12B are respectively polarized optical photomicrographimages and DSC trace for BC3, illustrating the appearance of an unknownmesophase M₂, upon cooling below SmCP_(A) phase.

FIG. 13 is a polarized optical photomicrograph of BC9, illustrating thetexture of a crystalline modification appearing at 80° C. upon cooling.

FIG. 14 is a polarized optical photomicrograph of the texture of acrystalline modification of BC14 at 74° C. on cooling.

GENERAL DESCRIPTION OF THE INVENTION Materials and Measurements

All solvents used for the synthesis of the gold nanoclusters and the LCswere Aldrich purification grade purified by using a PureSolv™ solventpurification system (Innovative Tech. Inc.). 1H and 13C NMR spectra wereacquired using a Bruker Avance™ 300 MHz spectrometer, and MALDI-MSspectra were acquired using a Bruker Biflex™ IV (MALDI-TOF) instrumentwith a 337 nm laser, acquired in positive ion reflecting mode. Elementalanalysis was performed at Guelph Chemical Laboratories (Guelph, Ontario,Canada). Melting points, phase transition temperatures, and thecorresponding enthalpy values of all final bent-core compounds weredetermined by means of a Perkin-Elmer Pyris Diamond™ differentialscanning calorimeter (DSC), obtained on the first cycle of heating andcooling at a rate of 10° C./min. Images of LC textures were acquiredupon cooling at a rate of 2-3° C./min using an Olympus™ BX51-P polarizedlight microscope (POM) equipped with a Linkam™ LS530 heating/coolingstage.

Small-angle X-ray scattering (SAXS) measurements of the pure LCsemployed a Bruker-Nonius™ FR591 rotating-anode generator with a copperanode operated at 3.4 kW. The beam was collimated and focused withmirror-monochromator optics and the scattered radiation was detectedusing a Bruker Hi-Star™ wire (area) detector. Samples were sealed in 1mm diameter glass capillaries. Measurements were made at fixedsample-detector distances of 54 and 124 cm; the final refinement of theunit cell parameters was made using the data from the 54 cmconfiguration. In-situ temperature-dependent measurements employed acustom Linkam heating cell. Primary data analysis was performed usingDatasqueeze™. The changes of textures under electric field andspontaneous polarization were studied/measured in glass cells with ITOelectrodes (Instec) using an LCAS I LC-testbed (LC Vision). X-raydiffraction (XRD) patterns for gold nanoparticles were obtained on anMPD X'Pert™ system (PANalytical) using CuK_(α), radiation (40 kV, 200mA), measured in reflection geometry using a zero-background flat sampleholder. UV-vis spectra were obtained using a Varian Cary™ 5000UV-vis-NIR spectrophotometer, which was also interfaced with the LinkamLS350 heating/cooling stage for high-T measurements on thin LC filmsdoped with gold NPs. High-resolution transmission electron microscopy(HR-TEM) images were obtained on a Jeol™ ultra-high resolutionFEG-T/STEM instrument operating at an accelerating voltage of 200 kV. A10 μL drop of the isolated gold colloid solution was drop-cast on acarbon coated copper grid (400 mesh) and dried for 1 h. (TEM imageanalysis of more than 200 particles—Software: Scion Image Beta 4 andImage J).

Synthesis of Bent-Core Compounds

Detailed synthetic information of all intermediates 1-25 and all finalbent-core compounds BC1-BC16, including yields, as well as H/C NMR,MALDI-MS, and elemental analysis data are provided in the DETAILEDDESCRIPTION OF EXPERIMENTAL EXAMPLES below. Symmetrically substitutedbent-core compounds were synthesized according to Scheme 1, andasymmetric derivatives were prepared according to Scheme 2 followingstandard DCC esterification procedures. The xanthogenate (or xanthate)intermediates (8, 14, and 20) as well as BC7 were synthesized byreacting the Ω-bromoalkane substituted compounds with potassiumo-ethylxanthogenate. All thioacetate derivatives (BC9, BC14) wereprepared by a photochemical anti-Markovnikov addition to thealkene-terminated derivatives (BC8, BC13) using AIBN as radicalinitiator. The free thiols (BC5, BC10, and BC15) were then obtained bytreatment of the thioacetate derivatives with concentracted HCl inMeOH/THF under reflux.

Synthesis of the Gold Nanoclusters

All glassware was thoroughly cleansed with Aqua Regia, rinsed withdeionized water (Millipore, resistivity 18.2 MΩ), and dried at 120° C.overnight prior to use. Gold nanoparticles capped with hexanethiol andsimultaneously with either compound BC10 or BC15 were prepared accordingto a modified, one-phase Brust-Schiffrin procedure, without the use ofTOAB as a phase transfer agent, and characterized by H NMR, UV-vis,HR-TEM, and powder XRD. The average sizes of the gold nanoclusters asdetermined by HR-TEM and XRD are summarized in Table 1, and HR-TEMimages (obtained from a 1 mg/mL solutions of the gold nanoclusters intoluene) are provided in FIG. 5. High-resolution TEM images of (a) Au1and (b) Au2 obtained after drop-casting solutions (1 mg/mL) in tolueneon carbon-coated copper grids. The highlighted area in (b) is shown in amagnified view in (c). The models of the bent-core compound BC15 in (c)are drawn to scale. One can clearly see that the average distancebetween most of the Au NPs in the displayed segment of the TEM image asin (a) for Au1 and (b) for Au2 match the length of the bent-coremolecules. (Scale bars=5 nm).

The ratio of the two bent-core thiol derivatives BC10 and BC15 tohexanethiol capping the mixed-monolayer gold NP surface was estimatedusing characteristic peaks in the ¹H NMR spectra of the NPs, i.e. bycomparing the ratio of the integration of the methoxy peak at 4.03 ppm(due to compound BC10 or BC15) to the methyl peak at 0.89 ppm (due tohexane thiolate and compound BC10 or BC15). In both cases, the ratio wasdetermined to be approximately 1:1.

TABLE 1 Size (size distribution) of the gold nanoclusters Au1 andAu2.^(a)

Particle Size/nm Ratio-SR TEM XRD^(b) Au1 SC₆H₁₃/BC10 ~ 1:1 2.8 ± 0.63.9 ± 1.5 Au2 SC₆H₁₃/BC15 ~ 1:1 2.5 ± 0.5 2.4 ± 0.8 ^(a)The total numberof thiolates n (sum of hexane- and bent-core thiolates) covering thegold NP depends on the size of the NP core. ^(b)Calculated from thewide-angle powder XRD pattern using the Scherrer equation.

Preparation of LC/Gold NP Mixtures

Mixtures of 2.5, 5, 10, and 15 wt % of Au1 and Au2 in LCs BC1 and BC8were prepared by stirring (agitating) a solution of both components inanhydrous purification grade solvents (e.g. toluene or CH₂Cl₂). Thesolvent was then evaporated by a steady stream of N₂ over the open glassvials, and the mixtures were dried under vacuum for 18 hours. Prior toinvestigating the thin films sandwiched between non-treated microscopeglass slides or filling of polyimide coated ITO cells (cell gap: 5 μm,antiparallel planar alignment, low pre-tilt—Instec Inc.), all mixtureswere tempered at the isotropic/LC phase transition (˜107° C. afterinitial heating to the isotropic liquid phase and subsequent cooling),and continuously mixed. After cooling to room temperature under N₂,samples were taken for DSC measurements as well.

Mesomorphic Properties of Derivatives Bent-Core LC Compounds

The mesomorphic properties of all bent-core derivatives (BC1-BC16) wereinvestigated by POM, DSC, and some selected samples additionally bysmall-angle X-ray scattering. The data of these investigations aresummarized in Table 2, below.

At this point, it should be noted that compounds BC1, BC2, BC3, BC8, andBC13 with methyl- or alkene-terminated hydrocarbon chains werepreviously reported by other groups, and served in this work either asintermediates or as hosts for the final bent-core decorated goldnanoclusters. The discussion of the mesomorphic properties willtherefore focus on the novel symmetric and unsymmetric bromo-,xanthate-, thioacetate-, as well as thiol-terminated bent-corecompounds, identified as BC4, BC5, BC6 and BC7 (symmetric); and BC9,BC10, BC11, BC12, BC14, BC15 and BC16 (asymetric).

The most striking difference between the two series of novel symmetricand unsymmetric bent-core compounds is that, while none of the symmetricderivatives display any liquid crystalline behaviour, the majority ofthe unsymmetric derivatives do. In particular the bis(thioacetate), thebis(bromo)-, and the bis(xanthate) compounds BC4, BC6, and BC7 show aseries of crystal-crystal phase transitions as observed by DSC, but noformation of a typical LC texture could be observed by POM that could besheared between microscope glass slides. The lack of liquidcrystallinity of the bis(thiol)-terminated bent-core compound BC5 washere particularly surprising, but is most likely related to the abilityof the two thioalcohol groups to participate in intermolecular H-bondingto carbonyl groups of neighboring molecules disrupting the formation oflayers or layer segments (ribbons).

For the bis(thioacetate) BC4 with C11-spacers and the bis(xanthate) BC7with C12 spacers, although both samples can be supercooled by up to 30°C. below the melting point measured on heating, the bulkiness of theterminal groups appears to prevent the formation of tilted or non-tiltedLC layer structures (i.e. SmCP or SmAP phases) or ribbons organizing inCol_(r) (B1 phase) or Col_(ob) lattices.

The same trend continues for the two mono(thioacetate) derivatives BC9and BC14. Both compounds in their DSC traces show one major peak onheating at 84° C. and 91° C., respectively (BC14 shows an additionallow-T crystal-crystal phase transition), and two phase transition peaksduring the cooling runs (supercoolable by ˜10° C.), all with verysimilar phase tansition enthalpie values (see ESI). On cooling from theisotropic liquid phase, both compounds form textures between crossedpolarizers that closely resemble textures commonly observed for Col_(r)or Col_(ob) bent core LCs (see ESI). However, the viscosity of bothcompounds after the transition from the isotropic liquid phase to thelow-T phase is rather high, and the textures show no change under shear.SAXS measurements on the two compounds (performed on heating and coolingin steps as low as 0.5° C.) suggest the formation of disordered (BC14)or multi-layer crystalline phases (BC9, Cr_(Lam), layer spacing d≈19.1nm) on cooling, which do not show any ferro- or antiferrolectricswitching under an applied electric field.

For the two, structurally related mono(xanthate) derivatives (BC12 andBC16), despite the structural similarity to the bis(xanthate) BC7 andthe two mono(thioacetate) compounds, DSC, POM, and SAXS indicate theformation of a monotropic LC phase. The textures observed on coolingfrom the isotropic liquid phase are shown in FIG. 2.

SAXS/WAXS performed on both compounds are consistent with a centeredrectangular lattice of a Col_(r) phase (B1 phase) for BC12 with latticeparameters of a=7.4 nm and b=3.7 nm, and a hexagonal lattice of aCol_(h) phase for BC16 (that could also be interpreted as a distortedCol_(r) lattice) with a lattice parameter of a_(hex)=4.09 nm. Bothmesophases did not show any electro-optic response (switching) under anapplied field, and if both are considered Col_(r) phases, the 2Dlattices of these columnar phases are in the plane of the polarizationvector (corresponding to the bend direction).

Finally, for the two mono(thiol) derivatives BC10 and BC15, which differonly in the lengths of the hydrocarbon chains, only BC10 with a C9 chainand a C10 spacer between the rigid, bent-core and the terminal thiolgroup forms a monotropic LC phase, which is only observed in a verynarrow temperature interval at faster cooling rates (>3° C. min⁻¹).

The polarized optical micrographs for BC10 shown as (a) to (f) of FIG. 3were respectively obtained (a) on 1^(st) cooling from the isotropicliquid phase at 89.8° C. at 3° C. min⁻¹ (notice the start ofcrystallization in the upper right hand corner), (b) on further coolingat 3° C. min⁻¹ at 87.9° C., (c) on 2^(nd) heating with 3° C. min⁻¹ at95° C., (d) on cooling from the isotropic liquid phase at 96.8° C. at 1°C. min⁻¹, (e) on further cooling at 89.8° C. at 1° C. min⁻¹, and (f) at87.8 ° C. at 1° C. min⁻¹. Cooling from the isotropic liquid phase at 3°C. min⁻¹ produces a fan-like texture [FIG. 3 (a)] that can be sheared,but starts to crystallize out during this process. Further cooling atthe same rate results then in a complete crystallization of the entirethin films as shown in FIGS. 3( b) and 3(c).

This phase transition is also clearly observed by DSC performed at aheating/cooling rate of 10° C. min⁻¹ (see FIG. 4). At a slower coolingrate of 1° C. min⁻¹, crystallization of BC10 sets in at a much highertemperature than at faster cooling rates, and no further crystal-crystalphase transitions can be observed on further cooling [see FIGS. 3( d) to(f)]. Attempts to elucidate the structure of this metastable LC phaseusing SAXS/WAXS at cooling rates of about 4° C. min⁻ were regrettablyunsuccessful, likely due to the large temperature step size selected toachieve rapid cooling during SAXS experiments.

TABLE 2 Phase transition temperatures (T/° C.), corresponding phasetransition enthalpies values (ΔH/kJ mol⁻¹), and parameters extractedfrom SAXS experiments of compounds B1-B16.

SAXS/WAXS q₁, q₂, q₃ (Å⁻¹), hkl, transition temperatures (T/° C.)lattice parameters Compd. R₁ R₂ m n transition enthalpies (ΔH/kJ mol⁻¹)(nm) BC1^(24,31,32) CH₃ CH₃ 9 9 Cr₁ 88 Cr₂ 103 Cr₃ 111 (SmCP_(A) 107)Iso —^(c)   4.9   8.4    40.3    (18.9) BC2^(24,31,32) CH₃ CH₃ 11 11 Cr106 SmCP_(A) 116 Iso —^(c)   41.8    23.1 BC3^(24,33) CH═CH₂ CH═CH₂ 9 9Cr 101 (M₁ ^(a) 82 SmCP_(A) 93) Iso —^(c)  48.2  (^(b))   (16.6) BC4SCOCH₃ SCOCH₃ 11 11 Cr₁ 74 Cr₂ 76 Iso —^(d)   3.8  70.9 BC5 SH SH 11 11Cr 95 Iso —^(d)  31.8 BC6 Br Br 12 12 Cr₁ 74 Cr₂ 90 Cr₃ 103 Iso crystal 10.5  13.0   71.5 modifications (no wide angle peak at ~0.45 nm) BC7SCSOEt SCSOEt 12 12 Cr₁ 69 Cr₂ 76 Iso —^(d)    1.3  23.3 BC8²⁴ CH₃CH═CH₂ 9 8 Cr 107 (Col_(r) 99) Iso —^(c)   57.0   (17.0) BC9 CH₃ SCOCH₃9 10 Cr_(Lam) 84 Iso 1^(st) cooling: q₁:   43.8 0.147, q₂: 0.295; d =4.3 nm 2^(nd) cooling: q₁: 0.131, q₂: 0.166, q₃: 0.196, q₄: 0.228, q₅:0.264, q₆: 0.333; d = 19.1 nm BC10 CH₃ SH 9 10 Cr 98 (M₂ 86) Isometastable phase^(e)  37.7 (20.4) BC11 Br CH₃ 12 11 Cr₁ 78 Cr₂ 94 Isoq₁: . . . , q₂: . . . , q₃:  11.8 25.6 . . . , disordered crystal phasesBC12 Br SCSOEt 12 12 Cr₁ 68 Cr₂ 80 (Col_(r) 75) Iso q₁: . . . (200), q₂:. . .   74.3 32.8  (16.9) (310), q₃: . . . (400), q₄: . . . (220), a =7.4 nm, b = 3.7 nm BC13²⁴ CH₃ CH═CH₂ 11 9 Cr 94 Col_(r) 107 Iso —^(c) 28.1   16.8 BC14 CH₃ SCOCH₃ 11 11 Cr₁ 79 Cr₂ 91 Iso high-T: q₁: 0.179 13.0 35.2 (crystal), low-T: crystal modifications (no wide angle peak)BC15 CH₃ SH 11 11 Cr₁ 59 Cr₂ 88 Cr₃ 95 Iso q₁: . . . , q₂: . . . , q₃:    3.7   2.4 30.0 . . . , disordered crystal phases BC16 CH₃ SCSOEt 1110 Cr₁ 83 Cr₂ 86 (Col_(h) 79) Iso q₁: . . . (100), q₂: . . .   2.7  29.4  (15.4) (110), q₃: . . . (200), a_(hex) = 4.09 nm ^(a)Phasetransition and phase here called M₁ not reported in [31,33] (for POMimage see DETAILED DESCRIPTION, below). ^(b)Enthalpy of the shoulder inthe DSC trace not calculated. ^(c)SAXS not performed on known compounds.^(d)SAXS not performed for clearly crystalline compounds.^(e)Meta-stable phase not observable by SAXS.

Self-Assembly of Bent-Core LC Decorated Nanoclusters

Much of our research was devoted to the assembly of gold nanoclustersowing to the usefulness of these NP assemblies in electronic, opticaland photonics applications.

To evaluate if the special molecular packing of the bent-core moleculescould be used to organize gold nanoclusters into arrays, we preparedgold NPs using both mono(thiol) bent-core derivatives, Au1 using BC10and Au2 using BC15. The NPs were synthesised as mixedmonolayer-protected NPs to enhance the solubility in common organicsolvents as well as in the bent-core LC hosts described below (“Mixtureswith bent-core LC hosts”).

After drop-casting solutions of both mixed-monolayer gold NPs previouslysuspended in toluene at a concentration of about 1 mg mL⁻¹, both Au1 andAu2 formed large areas of somewhat regular spaced gold nanoclustersvisible in the HR-TEM images. At this point it should be noted that onehas to be careful with interpreting TEM images and discussingself-assembly of nanoscale particles, since TEM merely produces 2Dimages of three-dimensional objects. However, analysis of severaldifferent images obtained from the same TEM grid revealed that over 60%of the particles are spaced about 3.9 ±0.6 nm edge-to-edge and about 15%4.4 ±0.5 nm edge-to-edge, which relates well to the molecular length ofthe bent-core molecules capping the nanoclusters (L_(BC)˜4.8 nm). Hence,the model predicted in FIG. 1 appears to be a good representation forthe assembly of bent-core decorated gold nanoclusters out of solution. Avery similar self-assembly process was recently presented by Kumar andco-workers for gold NPs coated with triphenylene-based discotic LCs.

While the conditions for this process have not been optimized at thisstage, we have found that the assembly of the nanoclusters to besolvent-dependent in so far that changing toluene for another solventsuch as CH₂Cl₂ induces a significant degree of aggregation of the goldNPs into three-dimensional nanocluster domains that did not allow formeasuring particle-to-particle distances.

Mixtures with Bent-Core LC Hosts

As expected, the pure, isolated gold NPs Au1 and Au2 did not show anyliquid crystalline behaviour due to the high melting points (transitiontemperatures) of the bent-core thiols used, contrary to a report by Mehlet al. for rod-like LCs attached in a side-on fashion to gold NPs.Nevertheless, owing to their mixed monolayer capping, both NPs can bereasonably well dispersed in the two selected bent-core LC hosts, i.e.BC1 forming a SmCP_(A) phase and BC8 forming a Col_(r) phase withinteresting thermal, self-assembly and electro-optic effects.

Optically visible, a certain degree of a bent-core LC host-dependentaggregation of the gold NPs in the two different LC hosts provokes areddish-brown to purple colour change [red-shift of the surface plasmonresonance band from 529 nm of pure Au1 to 538 nm in BC1 and to 555 nm inBC8 [see detailed description of experimental examples, below]. Thisred-shift, detectable by ‘naked’ eye (FIG. 6) was also detected byUV-vis spectrophotometry of the binary mixtures in the LC phase of bothhosts (FIG. 7).

While the changed surrounding dielectric (toluene vs LC host) influencesthe spectral position of the SPR band, this effect, which was alsoobserved for Au2 in both, structurally almost identical LC host (thedifference is only in the terminal ═CH₂ group), indicates that thedifferent packing of the two bent-core hosts (SmCP_(A) vs Col_(r))influences the aggregation of the bent-core decorated NPs differently asthe position of the SPR band does not significantly change withtemperature (±3 nm).

Thermal characterization of the composites containing differentconcentrations of the bent-core decorated NPs in BC1 and BC8 (for achart of all DSC traces for Au1 in BC1 and BC8 (see the DETAILEDDESCRIPTION below) indicates that an increasing concentration of thegold NPs has only a minor influence on the phase transition temperatureson heating (melting point depressions of about −1 ° C. for BC1 and about−4 ° C. for BC8). From the DSC traces obtained for Au1 in BC1 on heatingit is also apparent, that an increasing concentration of the gold NPsincreases the phase transition enthalpies of the low-temperature Cr-Crphase transitions, where the NPs might serve as nucleation sites.

A more drastic effect, however, is observed on cooling. Here, anincrease in the NPs concentration results initially (at 2.5wt %) in asignificant and then in a gradual (up to 15wt %) decrease in the Iso-LCtransition temperature of about −3° C. to −4° C., and of about −10° C.for the LC-Cr phase transition, effectively broadening the temperatureinterval of both LC phases on cooling.

Motivated by recent reports on the effects of metal nanoclustersprimarily on the electro-optic response of nematic LCs, we alsoperformed initial experiments demonstrating how an increasingconcentration of the bent-core decorated gold NPs would affect theresponse of the SmCP_(A) host BC1 to an applied electric field(sandwiched between ITO-coated 5 μm LC test cells; polyimide alignmentlayers, low pre-tilt).

The textural change upon applying an electric field and the currentresponse to a triangular voltage in the SmCP_(A) phase of pure BC1 isshown in FIG. 8 and FIG. 10( a), respectively. FIG. 8 shows the texturesof the SmCP_(A) phase of pure BC1 at 0V (left) and at +100V (right).Cell gap: 5 μm, temperature: 95° C. The models below each POM image showthe tilt- and polarization direction of the molecules in the field-OFFstate at 0V (anticlinic, antiferroelectric, SmC_(A)P_(A)-left) and inthe field-ON state at +100V (synclinic, ferroelectric,SmC_(S)P_(F)-right). FIG. 10 provides three graphical representations ofcurrent response to a triangular voltage voltage in the SmCP_(A) phaseof (a) pure BC1, (b) BC1 doped with 2.5wt % Au1, and (c) BC1 doped with5wt % Au2 (cell gap: 5 μm, temperature: 95° C., applied voltage(peak-to-peak): (a), (b) V_(pp)=200 V; (c) V_(pp)=220 V, frequency: 10Hz).

The first important observation made performing these experiments isthat the mixtures of BC1 containing varying concentrations of Au1 or Au2do not display the characteristic circular domains as observed for pureBC1 shown in FIG. 8. All mixtures, more or less, show uncharacteristicmulti-domain textures with a different orientation of the smectic layernormal, which are likely the result of local defects induced by thesuspended nanoclusters. Nevertheless, all domains remainelectro-optically active and respond to an applied electric field. FIG.9 shows the multi-domain texture photographed at low frequency (0.3 Hz)to demonstrate the non-uniform current response of these multi-domains.

Most interesting, however, is the observation that while the alignmentof the SmCP_(A) phase of BC1 obviously suffers with the presence and anincreasing concentration of the gold NPs, measured values for thespontaneous polarization increase by ca. 17% for the the 5wt % Au1 inBC1 mixture (P_(pure BC1)=649±21 nC cm⁻², P_(BC1+5 wt % Au1)=757±37 nCcm⁻²). Similar increases were also found for

BC1 in mixtures containing up to 5wt % Au2. At the same time, theresponse times increase from about 0.3 ms for pure BC1 to about 0.4 msfor BC1 doped with the gold NPs. While we relate the polarizationincrease to an enhanced conductivity of the mixtures⁴⁴, these initialelectro-optic data are rather difficult to interpret at the currentstage considering the drastic textural changes (differences in alignmentas well as multi-domain formation). The outcome of these measurements,however, warrants more detailed investigations and experiments toclarify and explain the observed effects.

For example, while visual inspection of the thin films of BC1 containingthe gold NPs seem to indicate that the nanoclusters are reasonably welldispersed (FIG. 6), polarized optical photomicrographs of mixtures withhigher particle content (≧5 wt %) appear to show that the gold NPs beginforming one-dimensional NP-aggregates (assemblies) in the LC host matrix(FIG. 11). FIG. 11 is a polarized optical photomicrograph of the textureformed by 5wt % Au1 in BC1 on cooling at the transition from theisotropic liquid to the SmCP_(A) phase (100×). One polarizer is rotatedabout 15° to show the dark line-like aggregates, presumably the resultof aggregation of the NPs.

The extent of aggregation already hinted by UV-vis spectrophotometry(FIG. 7) as well as the conductivity (polarizability) of the bent-coredecorated mixed monolayer gold NPs become apparent for mixturescontaining ≧5wt % gold NPs with electro-optic test cells (cell gap: 5μm) filled with these mixtures short-circuiting from time to time uponapplying an electric field (making detailed testing of these mixturesvery difficult and not necessarily reproducible).

DETAILED DESCRIPTION OF EXPERIMENTAL EXAMPLES: SYNTHESIS, SELF-ASSEMBLYAND EFFECTS IN MIXTURES OF BENT-CORE LC GOLD DECORATED NANOCLUSTERS WITHBENT-CORE LC HOSTS Detailed Synthetic Information

General Considerations. All reagents used were purchased from SigmaAldrich and used as received. All solvents used were AldrichPurification grade, purified via a PureSolv solvent purification system(Innovative Technology Inc.), with the exception of t-butanol (AlfaAesar, 99%) and ethanol (technical grade). All reactions were conductedunder N₂ atmosphere, unless stated otherwise.

Intermediates 1-25

Methyl 4-(decyloxy)benzoate (1). Anhydrous K₂CO₃ (18.43 g, 0.13 mol) wasadded to 300 mL of CH₃CN, and the solution was degassed with N₂ for 20minutes. Methyl-4-hydroxybenzoate (6.27 g, 41.2 mmol) was added to thereaction flask, which was heated to 70° C., following which1-bromodecane (8.8 mL, 42.5 mmol) was added. The above solution wasrefluxed for 12 hours, and upon cooling the solvent was removed underreduced pressure. The residue was taken in CH₂Cl₂ (200 mL) and washedwith 1 M HCl (100 mL). The organic layer was washed with distilled H₂O(100 mL), and the solvent was removed under reduced pressure. Yield 12.0g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.90 (3

H, t, ³J=6.9 Hz, CH₃), 1.24-1.54 (14 H, m, CH₂), 1.81 (2 H, m,O—CH₂—CH₂), 3.90 (3 H, s, OCH₃), 4.01 (2 H, t, ³J=6.6 Hz, O—CH₂), 6.92(2 H, d, ³J=9.0 Hz, Ar—H), 7.99 (2H, d, ³J=9.0 Hz, Ar—H). ¹³C NMR: δ_(C)(CDCl₃; 75 MHz): 14.5, 23.0, 26.4, 29.5, 29.7, 29.9, 32.3, 52.2, 68.6,114.5, 122.7, 131.9, 163.4, 167.3.

Methyl 4-(dodecyloxy)benzoate (2). Synthesized as described above forcompound 1. Quantities: K₂CO₃ (8.63 g, 62 mmol),methyl-4-hydroxy-benzoate (4.75 g, 31 mmol), 1-bromododecane (7.6 mL, 32mmol). Yield 9.58 g (96%). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.88 (3 H, t,³J=6.9 Hz, CH₃), 1.21-1.51 (18 H, m, CH₂), 1.79 (2 H, m, O—CH₂—CH₂),3.88 (3 H, s, OCH₃), 4.00 (2 H, t, ³J=6.6 Hz, O—CH₂), 6.90 (2 H, d,³J=9.0 Hz, Ar—H), 7.98 (2 H, d, ³J=9.0 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃;75 MHz): 14.5, 23.1, 26.4, 29.5, 29.8, 29.9, 30.0, 30.1, 32.3, 52.2,68.6, 114.5, 122.7, 131.9, 163.4, 167.3.

1.3. Methyl 4-(dec-9-enyloxy)benzoate (3). Synthesized as describedabove for compound 1. Quantities: K₂CO₃ (18.2 g, 0.13 mol),methyl-4-hydroxy-benzoate (6.30 g, 41.4 mmol), 10-bromo-1-decene (8.6mL, 42.8 mmol). Yield 12.0 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz):1.23-1.51 (10 H, m, CH₂), 1.77 (2 H, m, O—CH₂—CH₂), 2.03 (2 H, m,CH₂═CH—CH₂), 3.85 (3 H, s, OCH₃), 3.95 (2 H, t, ³J=6.5 Hz, O—CH₂), 4.95(2 H, m, CH₂═CH), 5.79 (1 H, m, CH₂═CH), 6.87 (2 H, d, ³J=9.0 Hz, Ar—H),7.98 (2 H, d, ³J=9.0 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 26.0,28.9, 29.0, 29.1, 29.3, 29.4, 51.7, 68.1, 114.0, 114.2, 122.3, 131.5,139.0, 162.9, 166.7.

Methyl 4-(undec-10-enyloxy)benzoate (4). Synthesized as described abovefor compound 1. Quantities: K₂CO₃ (9.08 g, 66 mmol),methyl-4-hydroxy-benzoate (5.00 g, 33 mmol), 11-bromo-1-undecene (7.6mL, 34 mmol). Yield 10.1 g (quant). ¹NMR: δ_(H) (CDCl₃; 300 MHz):1.24-1.52 (12 H, m, CH₂), 1.80 (2 H, m, O—CH₂—CH₂), 2.04 (2 H, m,CH₂═CH—CH₂), 3.87 (3 H, s, OCH₃), 4.00 (2 H, t, ³J=6.5 Hz, O—CH₂), 4.95(2 H, m, CH₂═CH), 5.82 (1 H, m, CH₂═CH), 6.90 (2 H, d, ³J=9.0 Hz, Ar—H),7.97 (2 H, d, ³J=9.0 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 26.4,29.3, 29.5, 29.7, 29.8, 29.9, 34.2, 52.2, 68.6, 114.45, 114.5, 122.7,131.9, 139.6, 163.4, 167.3.

4-(10-Bromodecyloxy)benzaldehyde (5). Synthesized as described above forcompound 1. Quantities: K₂CO₃ (4.75 g, 34 mmol), p-hydroxybenzaldehyde(3.57 g, 29 mmol), 1,10-dibromodecane (8.6 mL, 38 mmol). Yield 10.0 g(quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.22-1.52 (12 H, m, CH₂), 1.80(4 H, m, O—CH₂—CH₂/Br—CH₂—CH₂), 3.36 (2 H, t, ³J=6.9 Hz, Br—CH₂), 4.00(2 H, t, ³J=6.5 Hz, O—CH₂), 6.95 (2 H, d, ³J=8.7 Hz, Ar—H), 7.79 (2 H,d, ³J =8.8 Hz, Ar—H), 9.84 (1 H, s, COH). ¹³C NMR: δ_(C) (CDCl₃; 75MHz): 25.9, 28.1, 28.7, 29.0, 29.3, 29.4, 29.5, 32.8, 34.0, 68.4, 114.7,129.7, 131.9, 164.2, 190.7.

4-(12-Bromododecyloxy)benzaldehyde (6). Synthesized as described abovefor compound 1. Quantities: K₂CO₃ (4.6 g, 33 mmol), p-hydroxybenzaldehye(3.27 g, 27 mmol), 1,10-dibromododecane (11.56 g, 35 mmol). Yield 7.0 g(70%). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.24-1.52 (16 H, m, CH₂), 1.84 (4H, m, O—CH₂—CH₂/Br—CH₂—CH₂), 3.40 (2 H, t, ³J=6.9 Hz, Br—CH₂), 4.06 (2H, t, ³J=6.5 Hz, O—CH₂), 6.98 (2 H, d, ³J=8.7 Hz, Ar—H), 7.82 (2 H, d,³J=8.8 Hz, Ar—H), 9.88 (1 H, s, COH). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz):26.3, 28.6, 29.1, 29.4, 29.7, 29.8, 29.9, 33.2, 34.4, 68.8, 115.1,130.1, 132.3, 164.6, 191.1.

4-(10-Bromodecyloxy)benzoic acid (7). Resorcinol (4.16 g, 38 mmol) and 5(10.0 g, 29 mmol) were dissolved in t-butanol (600 mL) through gentleheating to 70° C. The solution was cooled to room temperature, and asolution of NaH₂PO₄·H₂O (13.7 g, 88 mmol) and NaClO₂ (15.3 g, 170 mmol)in deionized H₂O (100 mL) was added dropwise to the flask over a periodof 10 minutes. The purple-red mixture was stirred overnight, followingwhich it faded to a pale yellow colour. Volatile components wereremoved, and the residue was taken in hexane (200 mL) and 1 M HCl (200mL). The white precipitate was filtered and washed profusely withdistilled H₂and hexane. Yield 10.5 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300MHz): 1.26-1.55 (12 H, m, CH₂), 1.86 (4 H, m, O—CH₂—CH₂/Br—CH₂—CH₂),3.44 (2 H, t, ³J=6.8 Hz, Br—CH₂), 4.04 (2 H, t, ³J=6.5 Hz, O—CH₂), 6.95(2 H, d, ³J=8.9 Hz, Ar—H), 8.07 (2 H, d, ³J=8.9 Hz, Ar—H). ¹³C NMR:δ_(C) (CDCl₃; 75 MHz): 26.0, 28.1, 28.7, 29.0, 29.3, 29.4, 32.8, 34.0,68.3, 114.2, 121.4, 132.3, 163.7, 171.5.

4-(10-(Ethoxycarbonothioylthio)decyloxy)benzoic acid (8). Compound 7(2.49 g, 7 mmol) was dissolved in 600 mL of acetone that had been driedovernight over activated molecular sieves (4 Å), potassium o-ethylxanthogenate (3.53 g, 22 mmol) was added to the flask, and the mixturewas let to stir for 3 days in the dark at 4° C. The solvent wasevaporated, and the residue was taken in CH₂Cl₂ (300 mL) and washed with1 M HCl (50 mL). The product was then selectively precipitated fromdichloromethane through dropwise addition of petroleum ether. Yield 2.79g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.24-1.52 (15 H, m,CH₂/O—CH₂—CH₃), 1.69 (2 H, m, S—CH₂—CH₂), 1.81 (2 H, m, O—CH ₂—CH₂),3.11 (2 H, t, ³J=7.3 Hz, SCH₂), 4.02 (2 H, t, ³J=6.5 Hz, O—CH₂), 4.65 (2H, q, ³J=7.1 Hz, O—CH₂—CH₃), 6.93 (2 H, d, ³J=8.8 Hz, Ar—H), 8.04 (2 H,d, ³J=8.7 Hz, Ar—H).

4-(12-Bromododecyloxy)benzoic acid (9). Synthesized as described abovefor compound 7. Quantities: resorcinol (2.69 g, 24 mmol), 6 (7.0 g, 19mmol), NaH₂PO₄·H₂O (8.87 g, 57 mmol), NaClO₂ (9.92 g, 110 mmol). Yield7.32 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.24-1.52 (16 H, m,CH₂), 1.84 (4 H, m, O—CH₂—CH₂/Br—CH₂—CH₂), 3.40 (2 H, t, ³J=6.9 Hz,Br—CH₂), 4.06 (2 H, t, ³J=6.5 Hz, O—CH₂), 6.93 (2 H, d, ³J=9.0 Hz,Ar—H), 8.04 (2 H, d, ³J=8.9 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz):26.0, 28.2, 28.7, 29.1, 29.3, 29.4, 29.5, 32.8, 34.0, 68.3, 114.2,121.3, 132.3, 163.7, 171.4.

4-Formylphenyl 4-(decyloxy)benzoate (10). KOH (3.78 g, 67.6 mmol) wasadded to a solution of 1 (12.0 g, 41.0 mmol) dissolved in 250 mL of hotEtOH, and the mixture was refluxed for 24 hours. The solvent wasfiltered off, and following drying over P₂O₅ the white solid wassuspended in 300 mL of toluene, and refluxed with oxalyl chloride (13.4mL, 158.54) for 6 hours. Volatile components were removed, the yellowsolid was taken in CH₂Cl₂ (100 mL), and added to a stirred solutioncontaining p-hydroxybenzaldehyde (5.26 g, 43.1), triethylamine (36 mL,0.261 mol), and DMAP (0.28 g, 2.3 mmol) in CH₂Cl₂ (100 mL). The mixturewas let to stir at room temperature for three hours, and then heated toreflux for twelve hours. Following cooling to room temperature, theorganic layer was washed with 1 M HCl (2×100 mL), and then distilledwater (100 mL). The solvent was removed, and the product was obtained asan off-white solid following recrystallization from ethanol. Yield (8.5g, 54%). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.91 (3 H, t, ³J=6.8 Hz, CH₃),1.21-1.58 (14 H, m, CH₂), 1.85 (2 H, m, O—CH₂—CH₂), 4.07 (2 H, t, ³J=6.5Hz, O—CH₂), 7.00 (2 H, d, ³J=9.0 Hz, Ar—H), 7.42 (2 H, d, ³J=8.5 Hz,Ar—H), 7.98 (2 H, d, ³J=8.6 Hz, Ar—H), 8.16 (2 H, d, ³J=9.0 Hz, Ar—H),10.03 (1 H, s, COH). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.5, 23.1, 26.4,29.5, 29.7, 29.8, 30.0, 32.3, 68.8, 114.8, 121.2, 123.0, 131.6, 132.8,134.3, 156.3, 164.3, 164.6, 191.4.

4-Formylphenyl 4-(dodecyloxy)benzoate (11). Synthesized as describedabove for compound 10. Quantities: 2 (9.58 g, 30 mmol), KOH (2.34, 42mmol), oxalyl chloride (12 mL, 140 mmol), p-hydroxybenzaldehyde (4.38 g,36 mmol), triethylamine (32 mL, 0.23 mol), DMAP (0.19 g, 1.6 mmol).Yield 11.6 g (97%). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.89 (3 H, t, ³J=6.9Hz, CH₃), 1.21-1.51 (18 H, m, CH₂), 1.83 (2 H, m, O—CH₂—CH₂), 4.05 (2 H,t, ³J=6.6 Hz, O—CH₂), 6.99 (2 H, d, ³J=9.0 Hz, Ar—H), 7.40 (2 H, d,³J=8.5 Hz, Ar—H), 7.97 (2 H, d, ³J=8.6 Hz, Ar—H), 8.16 (2 H, d, ³J=9.0Hz, Ar—H), 10.0 (1 H, s, COH). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.5,23.1, 26.4, 29.5, 29.6, 29.7, 32.2, 68.8, 114.8, 121.2, 123.0, 131.6,132.8, 134.3, 156.3, 164.3, 164.6, 191.4.

4-Formylphenyl 4-(dec-9-enyloxy)benzoate (12). Synthesized as describedabove for compound 10. Quantities: 3 (12.0 g, 41.3 mmol), KOH (3.62 g,64.7 mmol), oxalyl chloride (12 mL, 0.15 mol), p-hydroxybenzaldehyde(5.25 g, 43.0 mmol), triethylamine (35 mL, 0.25 mol), DMAP (0.25 g, 2.0mmol). Yield 5.6 g (36%). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.27-1.57 (10H, m, CH₂), 1.85 (2 H, m, O—CH₂—CH₂), 2.07 (2 H, m, CH₂═CH—CH₂), 4.07 (2H, t, ³J=6.6 Hz, O—CH₂), 4.99 (2 H, m, CH₂═CH), 5.84 (1 H, m, CH₂═CH),7.00 (2 H, d, ³J=9.0 Hz, Ar—H), 7.42 (2 H, d, ³J=8.5 Hz, Ar—H), 7.98 (2H, d, ³J=8.6 Hz, Ar—H), 8.16 (2 H, d, ³J=9.0 Hz, Ar—H), 10.03 (1 H, s,COH). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 26.4, 29.3, 29.4, 29.5, 29.7,29.8, 34.2, 68.8, 114.6, 114.8, 121.2, 123.0, 131.6, 132.8, 134.3,139.5, 156.3, 164.3, 164.6, 191.4.

4-Formylphenyl 4-(undec-10-enyloxy)benzoate (13). Synthesized asdescribed above for compound 10. Quantities: 4 (10.10 g, 33 mmol), KOH(2.46, 45 mmol), oxalyl chloride (13 mL, 148 mmol),p-hydroxybenzaldehyde (4.6 g, 38 mmol), triethylamine (33.7 mL, 0.24mol), DMAP (0.20 g, 1.6 mmol). Yield 8.9 g (71%). ¹HNMR: δ_(H) (CDCl₃;300 MHz): 1.24-1.52 (12 H, m, CH₂), 1.83 (2 H, m, O—CH₂—CH₂), 2.04 (2 H,m, CH₂═CH—CH₂), 4.05 (2 H, t, ³J=6.5 Hz, O—CH₂), 4.95 (2 H, m, CH₂═CH),5.82 (1 H, m, CH₂═CH), 6.99 (2 H, d, ³J=9.0 Hz, Ar—H), 7.40 (2 H, d,³J=8.5 Hz, Ar—H), 7.96 (2 H, d, ³J=8.6 Hz, Ar—H), 8.14 (2 H, d, ³J=9.0Hz, Ar—H), 10.0 (1 H, s, COH). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 26.4,29.3, 29.5, 29.5, 29.7, 29.8, 29.9, 34.2, 68.8, 114.6, 114.8, 121.2,123.0, 131.6, 132.8, 134.3, 139.6, 156.3, 164.3, 164.6, 191.4.

4-Formylphenyl 4-(10-(ethoxycarbonothioylthio)decyloxy)benzoate (14).p-Hydroxybenzaldehyde (0.37 g, 3.0 mmol), 8 (1.2 g, 3.0 mmol), and DMAP(0.04 g, 0.3 mmol) were dissolved in 300 mL of CH₂Cl₂. DCC (1.24 g, 6.0mmol) was added to reaction flask which was stirred at room temperaturefor three days. The solvent was removed under reduced pressure, and theresidue purified using column chromatography (CH₂Cl₂:EtOH, 10:0.05). Theproduct was then recrystallized from ethanol. Yield 0.3 g (20%). ¹HNMR:δ_(H) (CDCl₃; 300 MHz): 1.24-1.52 (15 H, m, CH₂/O—CH₂—CH₃), 1.69 (2 H,m, S—CH₂—CH₂), 1.81 (2 H, m, O—CH₂—CH₂), 3.11 (2 H, t, ³J=7.3 Hz, SCH₂),4.02 (2 H, t, ³J=6.5 Hz, O—CH₂), 4.65 (2 H, q, ³J=7.1 Hz, O—CH₂—CH₃),6.99 (2 H, d, ³J=8.9 Hz, Ar—H), 7.40 (2 H, d, ³J=8.5 Hz, Ar—H), 7.96 (2H, d, ³J=8.6 Hz, Ar—H), 8.14 (2 H, d, ³J=8.9 Hz, Ar—H), 10.0 (1 H, s,COH). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 13.8, 25.9, 28.1, 28.3, 28.8,29.1, 29.3, 29.4, 35.9, 68.4, 69.7, 114.4, 120.8, 122.6, 131.2, 132.4,133.9, 155.9.

4-Formylphenyl-4-(12-bromododecyloxy)benzoate (15). Synthesized asdescribed for the preparation of compound 14. Quantities:p-hydroxybenzaldehyde (1.78 g, 15 mmol), 9 (5.5 g, 14 mmol), DMAP (0.25g, 2.0 mmol), DCC (6.54 g, 32 mmol). Yield 5.2 g (79%). ¹H NMR: δ_(H)(CDCl₃; 300 MHz): 1.24-1.52 (12 H, m, CH₂), 1.84 (4 H, m,O—CH₂—CH₂/Br—CH₂—CH₂), 3.40 (2 H, t, ³J=6.9 Hz, Br—CH₂), 4.06 (2 H, d,³J=6.5 Hz, O—CH₂), 6.99 (2H, d, ³J=8.9 Hz, Ar—H), 7.40 (2 H, d, ³J=8.5Hz, Ar—H), 7.97 (2 H, d, ³J=8.6 Hz, Ar—H), 8.14 (2 H, d, ³J=8.9 Hz,Ar—H), 10.00 (1 H, s, COH). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 13.8, 25.9,28.1, 28.3, 28.8, 29.1, 29.3, 29.3, 29.4, 35.9, 68.4, 69.7, 114.4,120.8, 122.6, 131.2, 132.4, 133.9, 155.9.

4-(4-(Decyloxy)benzoyloxy)benzoic acid (16). Synthesized as describedabove for compound 7. Quantities: resorcinol (3.18 g, 28.9 mmol), 10(8.5 g, 22 mmol), NaH₂PO₄·H₂O (10.39 g, 66.6 mmol), NaClO₂ (11.65 g,0.13 mol). Yield 8.8 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.91 (3H, t, ³J=6.8 Hz, CH₃), 1.23-1.59 (14 H, m, CH₂), 1.85 (2 H, m,O—CH₂—CH₂), 4.07 (2 H, t, ³J=6.5 Hz, O—-CH₂), 7.00 (2 H, d, ³J=8.9 Hz,Ar—H), 7.36 (2 H, d, ³J=8.6 Hz, Ar—H), 8.17 (2 H, d, ³J=8.9 Hz, Ar—H),8.22 (2 H, d, ³J=8.6 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.5,23.1, 26.4, 29.5, 29.7, 29.8, 30.0, 32.3, 68.8, 114.8, 121.4, 122.4,127.0, 132.3, 132.8, 156.0, 164.2, 164.7, 171.7.

4-(4-(Dodecyloxy)benzoyloxy)benzoic acid (17). Synthesized as describedabove for compound 7. Quantities: resorcinol (1.79 g, 16 mmol), 11 (5.52g, 13 mmol), NaH₂PO₄·H₂O (6.29 g, 40 mmol), NaClO₂ (7.03 g, 77 mmol).Yield 5.55 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.89 (3 H, t,³J=6.9 Hz, CH₃), 1.17-1.71 (18 H, m, CH₂), 1.83 (2 H, m, O—CH₂—CH₂),4.05 (2 H, t, ³J=6.6 Hz, O—CH₂), 6.99 (2 H, d, ³J=8.9 Hz, Ar—H), 7.35 (2H, d, ³J=8.6 Hz, Ar—H), 8.14 (2 H, d, ³J=8.9 Hz, Ar—H), 8.17 (2 H, d,³J=8.6 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 300 MHz): 14.1, 22.7, 26.0,29.1, 29.3, 29.5, 29.6, 29.6, 29.7, 31.9, 68.4, 114.4, 120.9, 122.0,126.5, 131.9, 132.4, 155.5, 170.3.

4-(4-(Dec-9-enyloxy)benzoyloxy)benzoic acid (18). Synthesized asdescribed above for compound 7. Quantities: resorcinol (2.11 g, 19.1mmol), 12 (5.6 g, 14.7 mmol), NaH₂PO₄·H₂O (6.89 g, 44.2 mmol), NaClO₂(7.72 g, 85.4 mmol). Yield 5.8 g (quant). ¹H NMR: δ_(H) (CDCl₃; 300MHz): 1.27-1.57 (10 H, m, CH₂), 1.85 (2 H, m, O—CH₂—CH₂), 2.08 (2 H, m,CH₂═CH—CH₂), 4.07 (2 H, t, ³J=6.6 Hz, O—CH₂), 4.99 (2 H, m, CH₂═CH),5.84 (1 H, m, CH₂═CH), 7.00 (2 H, d, ³J=8.9 Hz, Ar—H), 7.36 (2 H, d,³J=8.6 Hz, Ar—H), 8.17 (2 H, d, ³J=8.9 Hz, Ar—H), 8.22 (2 H, d, ³J=8.6Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 26.4, 29.3, 29.4, 29.5, 29.7,29.8, 34.2, 68.7, 114.6, 114.8, 121.34, 122.4, 127.0, 132.8, 139.5,156.0, 164.2, 164.7, 171.7.

4-(4-(Undec-10-enyloxy)benzoyloxy)benzoic acid (19). Synthesized asdescribed above for compound 7. Quantities: resorcinol (1.71 g, 16mmol), 13 (5.07 g, 13 mmol), NaH₂PO₄·H₂O (5.32 g, 39 mmol), NaClO₂ (6.71g, 74 mmol). Yield 5.34 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz):1.24-1.52 (12 H, m, CH₂), 1.83 (2 H, m, O—CH₂—CH₂), 2.04 (2 H, m,CH₂═CH—CH₂), 4.05 (2 H, t, ³J=6.5 Hz, O—CH₂), 4.95 (2 H, m, CH₂═CH),5.82 (1 H, m, CH₂═CH), 6.99 (2 H, d, ³J=8.9 Hz, Ar—H), 7.34 (2 H, d,³J=8.6 Hz, Ar—H), 8.16 (2 H, d, ³J=8.9 Hz, Ar—H), 8.20 (2 H, d, ³J=8.6Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 26.0, 28.9, 29.1, 29.3, 29.4,29.5, 33.8, 68.4, 114.1, 114.4, 121.0, 122.0, 126.5, 131.9, 132.4,139.2, 155.5, 163.8, 170.6.

4-(4-(10-(Ethoxycarbonothioylthio)decyloxy)benzoyloxy)benzoic acid (20).Synthesized as described above for compound 7. Quantities: resorcinol(0.09 g, 0.78 mmol), 14 (0.30 g, 0.6 mmol), NaH₂PO₄·H₂O (0.28 g, 1.8mmol), NaClO₂ (0.31 g, 3.5 mmol). Yield 0.31 g (quant.). ¹H NMR: δ_(H)(CD₃OD; 300 MHz): 1.24-1.73 (15 H, m, CH₂/O—CH₂—CH₃), 1.83 (4 H, m,S—CH₂—CH₂/O—CH₂—CH₂), 2.80 (2 H, d, ³J=7.3 Hz, SCH₂), 4.11 (2 H, d,³J=6.2 Hz, OCH₂), 4.85 (overlapping with solvent, O—CH₂—CH₃), 7.08 (2 H,d, ³J=8.9 Hz, Ar—H), 7.35 (2 H, d, ³J=8.5 Hz, Ar—H), 8.13 (4H, m, Ar—H).

4-(4-(12-Bromododecyloxy))benzoyloxy)benzoic acid (21). Synthesized asdescribed above for compound 7. Quantities: resorcinol (0.73 g, 6.6mmol), 15 (2.50 g, 5.1 mmol), NaH₂PO₄·H₂O (2.39 g, 15 mmol), NaClO₂(2.67 g, 30 mmol). Yield 2.58 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300MHz): 1.24-1.52 (16 H, m, CH₂), 1.84 (4 H, m, O—CH₂—CH₂/Br—CH₂—CH₂),3.40 (2 H, d, ³J=6.9 Hz, Br—CH₂), 4.06 (2 H, t, ³J=6.5 Hz, O—CH₂), 6.99(2 H, d, ³J=8.9 Hz, Ar—H), 7.30 (2 H, d, ³J=8.6 Hz, Ar—H), 8.16 (2 H, d,³J=8.9 Hz, Ar—H), 8.20 (2 H, d, ³J=8.6 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃;75 MHz): 26.0, 28.2, 28.7, 29.1, 29.3, 29.4, 29.5, 30.9, 32.8, 34.0,68.4, 114.4, 121.0, 122.0, 126.6, 131.8, 132.4, 155.4, 163.8, 164.3,169.8.

4-(4-(12-(Ethoxycarbonothioylthio)dodecyloxy)benzoyloxy)benzoic acid(22). Synthesized as described above for compound 8. Quantities:potassium o-ethyl xanthogenate (5.0 g, 31.2 mmol), 21 (0.30 g, 0.6mmol). Yield 0.3 g (quant.). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.23-1.57(15 H, m, CH₂/O—CH₂—CH₃), 1.71 (2 H, m, S—CH₂—CH₂), 1.85 (2 H, m,O—CH₂—CH₂), 3.14 (2 H, t, ³J=7.5 Hz, SCH₂), 4.07 (2 H, t, ³J=6.2 Hz,OCH₂), 4.67 (2 H, q, ³J=7.1 Hz, O—CH₂—CH₃), 7.00 (2 H, d, ³J=8.8 Hz,Ar—H), 7.36 (2 H, d, ³J=8.6 Hz, Ar—H), 8.16 (2 H, d, ³J=8.8 Hz, Ar—H),8.22 (2 H, d, ³J=8.6 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.2,26.4, 28.8, 29.3, 29.5, 29.75, 29.85, 29.9, 30.0, 36.3, 68.8, 70.1,114.8, 121.4, 122.4, 127.0, 132.3, 132.8, 156.0, 164.2, 164.7, 171.7.

4-((3-Hydroxyphenoxy)carbonyl)phenyl 4-(decyloxy)benzoate (23). Compound16 (2.05 g, 5.2 mmol) was suspended in toluene (100 mL), and refluxedwith oxalyl chloride (2.0 mL, 23.2 mmol) for five hours. Volatilecomponents were removed, and the white solid was taken in CH₂Cl₂ (50 mL)and added dropwise while stirring to a solution containing resorcinol(1.23 g, 11.2 mmol), triethylamine (5.4 mL, 39 mmol), and DMAP (0.06 g,0.52 mmol). Following stirring at room temperature for 12 hours, themixture was then refluxed for twenty four hours. The solvent was removedunder reduced pressure, and the residue purified by columnchromatography (CH₂Cl₂:EtOH, 10:0.03, and then CH₂Cl₂:EtOH, 10:0.3). Theproduct was then recrystallized from ethanol. Yield (1.6 g, 64%). ¹HNMR: δ_(H) (CDCl₃; 300 MHz): 0.92 (3 H, t, ³J=6.9 Hz, CH₃), 1.23-1.60(14 H, m, CH₂), 1.86 (2 H, m, O—CH₂—CH₂), 4.07 (2 H, t, ³J=6.5 Hz,O—CH₂), 6.15 (1 H, bs, OH), 6.69 (2 H, m, Ar—H), 6.78 (1 H, d, ³J=8.3Hz, Ar—H), 7.01 (2 H, d, ³J=8.9 Hz, Ar—H), 7.25 (1 H, t, ³J=8.5 Hz,Ar—H), 7.38 (2 H, d, 3J=8.8 Hz, Ar—H), 8.18 (2 H, d,³J=8.9 Hz, Ar—H),8.27 (2 H, d, ³J=8.8 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.5,23.1, 26.4, 29.5, 29.7, 29.8, 30.0, 32.3, 68.8, 109.8, 113.8, 113.9,114.9, 121.2, 122.6, 127.2, 130.5, 132.3, 132.9, 152.0, 155.8, 157.4,164.3, 165.0, 165.3.

4-((3-Hydroxyphenoxy)carbonyl)phenyl 4-(dodecyloxy)benzoatebenzoate(24). Synthesized as described for the preparation of compound 23.Quantities: 21 (2.9 g, 7 mmol), oxalyl chloride (2.3 mL, 27.6 mmol),resorcinol (2.3 g, 2.1 mol), triethylamine (7.4 mL, 53 mmol), DMAP (0.09g, 0.7 mmol). Yield 1.37 g (38%). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.91(3 H, t, ³J=6.9 Hz, CH₃), 1.23-1.56 (18 H, m, CH₂), 1.85 (2 H, m,O—CH₂—CH₂), 4.08 (2 H, t, ³J=6.6 Hz, O—CH₂), 4.98 (1 H, bs, OH), 6.76 (2H, m, Ar—H), 6.83 (1 H, d, ³J=8.3 Hz, Ar—H), 7.01 (2 H, d, ³J=9.0 Hz,Ar—H), 7.30 (1 H, t, ³J=8.5 Hz, Ar—H), 7.39 (2 H, d, ³J=8.8 Hz, Ar—H),8.18 (2 H, d, ³J=8.9 Hz, Ar—H), 8.29 (2 H, d, ³J=8.8 Hz, Ar—H). ¹³C NMR:δ_(C) (CDCl₃; 75 MHz): 14.1, 22.7, 26.0, 29.1, 29.3, 29.55, 29.6, 29.65,31.9, 53.4, 68.4, 109.3, 113.1, 114.0, 114.4, 120.9, 122.1, 126.8,131.8, 132.4, 151.8, 155.4, 156.5, 163.8, 164.4.

4-((3-Hydroxyphenoxy)carbonyl)phenyl 4-(12-bromododecyloxy)benzoate(25). Synthesized as described for the preparation of compound 23.Quantities: 21 (1.5 g, 3 mmol), oxalyl chloride (1.6 mL, 18.9 mmol),resorcinol (0.66 g, 6 mol), triethylamine (3 mL, 23 mmol), DMAP (0.04 g,0.3 mmol). Yield 0.7 g (36%). ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.27-1.58(16 H, m, CH₂), 1.86 (4 H, m, O—CH₂—CH₂, Br—CH_(2—CH) ₂), 3.43 (2 H, t,³J=6.8 Hz, Br—CH₂), 4.07 (2 H, t, ³J=6.5 Hz, O—CH₂), 6.70 (2 H, m,Ar—H), 6.77 (1 H, d, ³J=8.1 Hz, Ar—H), 7.00 (2 H, d, ³J=8.8 Hz, Ar—H),7.25 (1 H, t, ³J=8.5 Hz, Ar—H), 7.37 (2 H, d, ³J=8.7 Hz, Ar—H), 8.17 (2H, d, ³J=8.8 Hz, Ar—H), 8.27 (2 H, d, ³J=8.7 Hz, Ar—H). ¹³C NMR: δ_(C)(CDCl₃; 75 MHz): 26.4, 28.6, 29.2, 29.5, 29.8, 29.8, 29.9, 33.2, 34.5,68.8, 109.7, 113.8, 113.9, 114.9, 121.2, 122.5, 127.2, 130.5, 132.3,132.9, 152.0, 155.8, 157.5, 164.3, 165.0, 165.2.

Bent-Core Derivatives BC1-BC16

1,3-Phenylene bis(4-(4-(decyloxy)benzoyloxy)benzoate) (BC1). Resorcinol(0.3 g, 2.5 mmol), 14 (1.89 g, 4.7 mmol), and DMAP (0.6 g, 5.1 mmol)were dissolved in 50 mL of CH₂Cl₂. DCC (2.07 g, 10.0 mmol) was added toreaction flask which was stirred at room temperature for 48 hours. Thesolvent was removed under reduced pressure, and the residue purifiedusing column chromatography (CH₂Cl₂:EtOH, 10:0.03). The product was thenselectively precipitated from CH₂Cl₂ through dropwise addition ofpetroleum ether. Yield 1.5 g (68%). EA: Found: C, 74.36; H, 7.16.C₅₄H₆₂O₁₀ requires C, 74.46; H, 7.17%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz):0.94 (6 H, t, ³J=6.7 Hz, CH₃), 1.19-1.60 (28 H, m, CH₂), 1.85 (4 H, m,O—CH₂—CH₂), 4.06 (4 H, t, ³J=6.4 Hz, O—CH₂), 7.00 (4 H, d, ³J=8.7 Hz,Ar—H), 7.22 (3 H, m, Ar—H), 7.39 (4 H, d, ³J=8.6 Hz, Ar—H), 7.50 (1 H,t, ³J=8.1 Hz, Ar—H), 8.17 (4 H, d, ³J=8.7 Hz, Ar—H), 8.28 (4 H, d,³J=8.6 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.6, 23.1, 26.4,29.5, 29.8, 30.0, 32.3, 68.8, 114.8, 116.2, 119.7, 121.4, 122.5, 127.0,130.2, 132.2, 132.8, 151.9, 155.9, 164.2, 164.4, 164.6. m/z (MALDI)893.63 [M+Na]⁺, C₅₄H₆₂NaO₁₀requires 893.42.

1,3-Phenylene bis(4-(4-(dodecyloxy)benzoyloxy)benzoate) (BC2).Synthesized as described for the preparation of compound BC1.Quantities: resorcinol (0.12 g, 1.1 mmol), 15 (0.97 g, 2.3 mmol), DMAP(0.02 g, 0.1 mmol), DCC (0.91 g, 4.4 mmol). Yield 0.53 g (53%). EA:Found: C, 74.98; H, 7.50. C₅₈H₇₀O₁₀ requires C, 75.13; H, 7.61%. ¹HNMR:δ_(H) (CDCl₃; 300 MHz): 0.89 (6 H, t, ³J=6.9 Hz, CH₃), 1.24-1.48 (36 H,m, CH₂), 1.84 (4 H, m, O—CH₂—CH₂—), 4.06 (4 H, t, ³J=6.5 Hz, O—CH₂),6.99 (4 H, d, ³J=9.0 Hz, Ar—H), 7.19 (3 H, m, Ar—H), 7.38 (4 H, d,³J=8.8 Hz, Ar—H), 7.50 (1 H, t, ³J=8.3 Hz, Ar—H), 8.16 (4 H, d, ³J=8.9Hz, Ar—H), 8.28 (4 H, d, ³J=8.8 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75MHz): 14.1, 22.7, 26.0, 29.1, 29.3, 29.5, 29.6, 29.7, 31.9, 68.4, 114.4,115.8, 119.3, 120.9, 122.1, 126.6, 129.9, 131.9, 132.4, 151.4, 155.5,163.8, 164.1, 164.3. m/z (MALDI) 950.06 [M+Na]⁺, C₅₈H₇₀NaO₁₀ requires949.49.

1,3-Phenylene bis(4-(4-(undec-10-enyloxy)benzoyloxy)benzoate) (BC3).Synthesized as described for the preparation of compound BC1.Quantities: resorcinol (0.13 g, 1.1 mmol), 17 (0.92 g, 2.2 mmol), DMAP(0.03 g, 0.2 mmol), DCC (0.92 g, 4.5 mmol). Yield 0.72 g (71%). EA:Found: C, 74.88; H, 7.22. C ₅₆H₆₂O₁₀ requires C, 75.14; H, 6.98%. ¹HNMR: δ_(H) (CDCl₃; 300 MHz): 1.24-1.43 (24 H, m, CH₂), 1.84 (4 H, m,O—CH₂—CH₂—), 2.04 (4 H, m, CH₂—CH═CH₂), 4.06 (4 H, t, ³J=6.5 Hz, O—CH₂),4.95 (4 H, m, CH═CH₂), 5.80 (2 H, m, CH═CH₂), 6.99 (4 H, d, ³J=8.9 Hz,Ar—H), 7.19 (3 H, m, Ar—H), 7.38 (4 H, d, ³J=8.7 Hz, Ar—H), 7.50 (1 H,t, ³J=8.3 Hz, Ar—H), 8.16 (4 H, d, ³J=8.9 Hz, Ar—H), 8.28 (4 H, d,³J=8.7 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 26.4, 29.3, 29.4,29.5, 29.7, 29.8, 29.9, 34.2, 68.8, 114.5, 114.8, 116.2, 119.7, 121.4,122.5, 127.0, 130.3, 132.3, 132.8, 139.6, 151.8, 155.9, 164.2, 164.5,164.7. m/z (MALDI) 918.25 [M+Na]⁺, C₅₆H₆₂NaO₁₀ requires 917.42.

1,3-Phenylene bis(4-(4-(11-(acetylthio)undecyloxy)benzoyloxy)benzoate)(BC4). Compound BC3 (0.81 g, 0.9 mmol), thioacetic acid (0.5 mL, 7.2mmol), and AIBN (0.1 g, 0.6 mmol) were dissolved in THF (50 mL), and thesolution was irradiated with UV light while stirring for 3 hours. Thesolvent was removed, and the residue purified by column chromatography(CH₂Cl₂:EtOH, 10:0.03). The product was selectively precipitated fromCH₂Cl₂ through dropwise addition of petroleum ether. Yield 0.9 g (93%).EA: Found: C, 68.37; H, 7.00. C₆₀H₇₀NaO₁₂S₂ requires C, 68.81; H, 6.74%.¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.27-1.65 (32 H, m, CH₂), 1.85 (4 H, m,O—CH₂—CH₂), 2.35 (6 H, s, COCH₃), 2.89 (2 H, t, ³J=7.3, SCH₂), 4.06 (4H, t, ³J=6.5 Hz, OCH₂), 6.99 (4 H, d, ³J=9.0 Hz, Ar—H), 7.22 (3 H, m,Ar—H), 7.40 (4 H, d, ³J=8.8 Hz, Ar—H), 7.50 (1 H, t, ³J=8.3 Hz, Ar—H),8.17 (4 H, d, ³J=8.9 Hz, Ar—H), 8.29 (4 H, d, ³J=8.8 Hz, Ar—H). ¹³C NMR:δ_(C) (CDCl₃; 75 MHz): 14.1, 22.7, 26.0, 28.8, 29.1, 29.35, 29.4, 29.5,29.55, 29.6, 29.65, 29.7, 31.9, 68.4, 114.4, 115.8, 119.3, 120.9, 122.1,126.6, 129.9, 131.8, 132.4, 151.4, 151.4, 155.5, 163.8, 164.1, 164.3,196.0. m/z (MALDI) 1069.64 [M+Na]⁺, C₆₀H₇₀NaO₁₂S₂ requires 1069.42.

1,3-Phenylene bis(4-(4-(11-mercaptoundecyloxy)benzoyloxy)benzoate)(BC5). Compound BC4 (0.2 g, 0.2 mmol) was dissolved in 50:50 THF/MeOH(20 mL), and following addition of 3 mL conc. HCl to the flask, themixture was heated to reflux for 6 hours. The mixture was let to cool toroom temperature, diluted with water (10 mL), and extracted with CH₂Cl₂(2×200 mL). The solvent was removed, and the residue purified by columnchromatography (CH₂Cl₂: EtOH, 10:0.03). The product was then selectivelyprecipitated from CH₂Cl₂ through dropwise addition of petroleum ether.Yield 0.11 g (60%). EA: Found: C, 69.37; H, 7.21. C₅₆H₆₆O₁₀S₂ requiresC, 69.83; H, 6.91%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.24-1.56 (30 H, m,CH₂ / SH), 1.63 (4 H, m, S—CH₂—CH₂), 1.85 (4 H, m, O—CH₂—CH₂), 2.55 (4H, q, ³J=7.4, SCH₂), 4.07 (4 H, t, ³J=6.5 Hz, OCH₂), 7.01 (4 H, d,³J=8.9 Hz, Ar—H), 7.22 (3 H, m, Ar—H), 7.40 (4 H, d, ³J=8.7 Hz, Ar—H),7.50 (1 H, t, ³J=8.2 Hz, Ar—H), 8.17 (4 H, d, ³J=8.9 Hz, Ar—H), 8.29 (4H, d, ³J=8.7 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 25.1, 26.4,28.8, 29.5, 29.7, 29.9, 29.9, 34.4, 53.8, 68.8, 114.8, 116.2, 119.7,121.4, 122.5, 127.0, 130.3, 132.3, 132.8, 151.8, 155.9, 164.2, 164.5,164.7. m/z (MALDI) 985.81 [M+Na]⁺, C₅₆H₆₆NaO₁₀S₂ requires 985.40.

1,3-Phenylene bis(4-(4-(12-bromododecyloxy)benzoyloxy)benzoate) (BC6).Synthesized as described for the preparation of compound BC1.Quantities: resorcinol (0.12 g, 1.1 mmol), 12 (1.0 g, 2.0 mmol), DMAP(0.03 g, 0.2 mmol), DCC (0.95 g, 4.6 mmol). Yield 0.56 g (48%). EA:Found: C, 64.60; H, 6.09. C₅₈H₆₈Br₂O₁₀ requires C, 64.21; H, 6.32%. ¹HNMR: δ_(H) (CDCl₃; 300 MHz): 1.24-1.52 (32 H, m, CH₂), 1.84 (8 H, m,O—CH₂—CH₂/Br—CH₂—CH₂), 3.40 (4 H, t, ³J=6.9 Hz, Br—CH₂), 4.06 (4 H, t,³J=6.5 Hz, O—CH₂), 6.99 (4 H, d, ³J=9.0 Hz, Ar—H), 7.19 (3 H, m, Ar—H),7.38 (4 H, d,³J=8.8 Hz, Ar—H), 7.50 (1 H, t, ³J=8.3 Hz, Ar—H), 8.16 (4H, d, ³J=8.9 Hz, Ar—H), 8.28 (4 H, d, ³J=8.8 Hz, Ar—H). ¹³C NMR: δ_(C)(CDCl₃; 75 MHz): 26.0, 28.2, 28.8, 29.1, 29.35, 29.4, 29.5, 32.8, 34.1,68.4, 114.4, 115.8, 119.3, 121.0, 122.2, 126.6, 129.9, 131.9, 132.4,151.4, 155.5, 163.8, 164.1, 164.3. m/z (MALDI) 1105.67 (100%) and1107.67 (51%) [M+Na]⁺, C₅₈H₆₈Br₂NaO₁₀ requires 1105.31 (51%) and 1107.31(100%).

1,3-Phenylenebis(4-(4-(12-(ethoxycarbonothioylthio)dodecyloxy)benzoyloxy) benzoate)(BC7).

Synthesized as described for the preparation of compound 8. Quantities:BC6 (0.10 g, 0.09 mmol), potassium o-ethyl xanthogenate (0.04 g, 0.2mmol). Yield 0.12 g (quant.). EA: Found: C, 65.16; H, 7.83. C₆₄H₇₈O₁₂S₄requires C, 65.84; H, 6.73%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 1.24-1.56(38 H, m, CH₂/O—CH₂—CH₃), 1.71 (2 H, m, S—CH₂—CH₂), 1.85 (4 H, m,O—CH₂—CH₂), 3.11 (4 H, t, ³J=7.4 Hz, SCH₂), 4.07 (4 H, t, ³J=6.5 Hz,O—CH₂), 4.67 (4 H, q, ³J=7.1 Hz, O—CH₂—CH₃), 7.01 (2 H, d,³J=8.7 Hz,Ar—H), 7.21 (3 H, m, Ar—H), 7.40 (4 H, d, ³J=8.5 Hz, Ar—H), 7.50 (1 H,t, ³J=8.1 Hz, Ar—H), 8.17 (4 H, d, ³J=8.7 Hz, Ar—H), 8.29 (4 H, d,³J=8.5 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 13.8, 26.0, 28.3,28.9, 29.1, 29.3, 29.4, 29.5, 35.9, 68.4, 69.7, 114.4, 115.8, 119.3,120.9, 122.1, 126.6, 129.9, 131.9, 132.4, 151.4, 155.5, 163.8, 164.1,164.3, 171.6. m/z (MALDI) 1189.33 [M+Na]⁺, C₆₄H₇₈NaO₁₂S₄ requires1189.43.

4-((3-(4-(4-(Dec-9-enyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl4-(decyloxy)-benzoate (BC8). Synthesized as described for thepreparation of compound BC1. Quantities: 23 (0.58 g, 1.2 mmol), 18 (0.51g, 1.3 mmol), DMAP (0.19 g, 1.6 mmol), DCC (0.5 g, 2.4 mmol). Yield 0.68g (58%). EA: Found: C, 74.69; H, 7.10. C₅₄H₆₀O₁₀ requires C, 74.63; H,6.96%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.93 (3 H, t, ³J=6.7 Hz, CH₃),1.18-1.61 (24 H, m, CH₂), 1.85 (4 H, m, O—CH₂—CH₂—), 2.09 (4 H, m,CH₂—CH═CH₂), 4.06 (4 H, t, ³J=6.4 Hz, O—CH₂), 5.01 (4 H, m, CH═CH₂),5.86 (2 H, m, CH═CH₂), 7.01 (4 H, d, ³J=8.7 Hz, Ar—H), 7.23 (3 H, m,Ar—H), 7.40 (4 H, d, ³J=8.6 Hz, Ar—H), 7.50 (1 H, t, ³J=8.1 Hz, Ar—H),8.18 (4 H, d, ³J=8.7 Hz, Ar—H), 8.27 (4 H, d, ³J=8.6 Hz, Ar—H). ¹³C NMR:δ_(C) (CDCl₃; 75 MHz): 14.2, 22.7, 26.0, 28.9, 29.1, 29.35, 29.4, 29.6,68.4, 114.3, 114.5, 115.8, 119.3, 121.0, 122.2, 126.6, 129.9, 131.8,132.4, 139.1, 151.5, 155.5, 163.8, 164.0, 164.2. m/z (MALDI) 891.43[M+Na]⁺, C₅₄H₆₀NaO₁₀ requires 891.41.

4-((3-(4-(4-(10-(Acetylthio)decyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl 4-(decyl-oxy)benzoate (BC9). Synthesized as described for thepreparation of compound BC4. Quantities: BC8 (0.55 g, 0.61 mmol),thioacetic acid (0.3 mL, 4.90 mmol), and AIBN (0.1 g, 0.61 mmol). Yield0.5 g (86%). EA: Found: C, 70.85; H, 6.91. C₅₆H₆₄O₁₁S requires C, 71.16;H, 6.82%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.91 (3 H, t, ³J=6.9 Hz, CH₃),1.21-1.66 (28 H, m, CH₂), 1.85 (4 H, m, O—CH₂—CH₂), 2.34 (3 H, s,COCH₃), 2.89 (2 H, t, ³J=7.3, SCH₂), 4.07 (4 H, t, ³J=6.5 Hz, OCH₂),7.01 (4 H, d, ³J=8.9 Hz, Ar—H), 7.21 (3 H, m, Ar—H), 7.40 (4 H, d,³J=8.7 Hz, Ar—H), 7.52 (1 H, t, ³J=8.1 Hz, Ar—H), 8.17 (4 H, d, ³J=8.8Hz, Ar—H), 8.30 (4 H, d, ³J=8.7 Hz, Ar—H). ¹C NMR: δ_(C) (CDCl₃; 75MHz): 14.5, 23.1, 26.35, 26.4, 29.2, 29.45, 29.5, 29.7, 29.8, 29.85,29.9, 30.0, 31.0, 32.3, 68.75, 68.8, 114.8, 116.2, 119.7, 121.3, 122.6,127.0, 130.3, 132.3, 132.8, 151.8, 155.9, 164.2, 164.5, 164.7, 196.4.m/z (MALDI) 967.39 [M+Na]⁺, C₅₆H₆₄NaO₁₁S requires 967.41.

4-((3-(4-(4-(Decyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl4-(10-mercaptodecyloxy) benzoate (BC10). Synthesized as described forthe preparation of compound 27. Quantities: BC9 (0.45 g, 0.48 mmol), 12MHCl (2 mL). Yield 0.26 g (60%). EA: Found: C, 71.44; H, 6.93. C₅₄H₆₂O₁₀Srequires C, 71.82; H, 6.92%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.91 (3 H,t, ³J=6.8 Hz, CH₃), 1.17-1.57 (27 H, m, CH₂/SH), 1.63 (2 H, m,S—CH₂—CH₂), 1.85 (4 H, m, O—CH₂—CH₂), 2.55 (2 H, q, ³J=7.2, SCH₂), 4.07(4 H, t, ³J=6.5 Hz, OCH₂), 7.01 (4 H, d, ³J=8.9 Hz, Ar—H), 7.21 (3 H, m,Ar—H), 7.40 (4 H, d, ³J=8.7 Hz, Ar—H), 7.52 (1 H, t, ³J=8.1 Hz, Ar—H),8.18 (4 H, d, ³J=8.8 Hz, Ar—H), 8.30 (4 H, d, ³J=8.7 Hz, Ar—H). ¹³C NMR:δ_(C) (CDCl₃; 75 MHz): 14.5, 23.1, 25.1, 26.4, 28.8, 29.45, 29.5, 29.7,29.75, 29.8, 29.9, 30.0, 32.3, 34.4, 68.75, 68.8, 114.8, 116.2, 119.7,121.3, 121.4, 122.6, 127.0, 130.3, 132.3, 132.8, 151.8, 155.9, 163.8,164.1, 164.3. m/z (MALDI) 941.36 [M+K]⁺, C₅₄H₆₂KO₁₀S requires 941.37.

4-((3-(4-(4-(12-Bromododecyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl4-(dodecyl-oxy)benzoate (BC11). Synthesized as described for thepreparation of compound BC1. Quantities: 25 (0.15 g, 0.25 mmol), 17(0.11 g, 0.25 mmol), DMAP (0.03 g, 0.25 mmol), DCC (0.10 g, 0.5 mmol).Yield 0.18 g (72%). EA: Found: C, 69.39; H, 7.13. C₅₈H₆₉BrO₁₀ requiresC, 69.24; H, 6.91%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.91 (3 H, t, ³J=6.8Hz, CH₃), 1.19-1.56 (34 H, m, CH₂), 1.85 (6 H, m, O—CH₂—CH₂/Br—CH₂—CH₂),3.43 (2 H, t, ³J=6.8 Hz, CH₂Br), 4.08 (4 H, t, ³J=6.5 Hz, OCH₂), 7.01 (2H, d, ³J=8.8 Hz, Ar—H), 7.21 (3 H, m, Ar—H), 7.40 (4 H, d, ³J=8.6 Hz,Ar—H), 7.52 (1 H, t, ³J=8.1 Hz, Ar—H), 8.18 (4 H, d, ³J=8.8 Hz, Ar—H),8.30 (4 H, d, ³J=8.6 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.5,23.1, 26.4, 28.6, 29.2, 29.5, 29.75, 29.8, 29.85, 29.9, 29.95, 30.0,32.3, 33.2, 34.4, 68.8, 114.7, 114.8, 116.2, 119.7, 121.4, 122.5, 127.0,130.2, 132.2, 132.25, 132.3, 132.8, 151.8, 151.85, 155.9, 164.2, 164.5,164.7. m/z (MALDI) 1028.00 (100%) and 1030.03 (97%) [M+Na]⁺,C₅₈H₆₉BrNaO₁₀ requires 1027.40 (100%) and 1029.40 (97%).

4-((3-(4-(4-(12-Bromododecyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl4-(12-(ethoxycarbonothioylthio)dodecyloxy)benzoate (BC12). Synthesizedas described for the preparation of compound BC1. Quantities: 25 (0.22g, 0.37 mmol), 22 (0.20 g, 0.37 mmol), DMAP (0.045 g, 0.37 mmol), DCC(0.15 g, 0.73 mmol). Yield 0.25 g (61%). EA: Found: C, 64.49; H, 6.81.C₆₁H₇₃BrO₁₁S₂ requires C, 65.05; H, 6.53%. ¹H NMR: δ_(H) (CDCl₃; 300MHz): 1.22-1.62 (35 H, m, CH₂/O—CH₂—CH₃), 1.71 (2 H, m, S—CH₂—CH₂), 1.87(6 H, m, O—CH₂—CH₂/Br—CH₂—CH₂), 3.13 (2 H, t, ³J=7.4 Hz, SCH₂), 3.42 (2H, t, ³J=6.8 Hz, CH₂Br), 4.07 (4 H, t, ³J=6.5 Hz, OCH₂), 4.66 (2 H, q,³J=7.1 Hz, O—CH₂—CH₃), 7.01 (2 H, d, ³J=8.7 Hz, Ar—H), 7.21 (3 H, m,Ar—H), 7.40 (4 H, d, ³J=8.5 Hz, Ar—H), 7.51 (1 H, t, ³J=8.1 Hz, Ar—H),8.17 (4 H, d, ³J=8.7 Hz, Ar—H), 8.30 (4 H, d, ³J=8.5 Hz, Ar—H). ¹³C NMR:δ_(C) (CDCl₃; 75 MHz): 13.8, 26.0, 28.2, 28.3, 28.8, 28.9, 29.0, 29.3,29.35, 29.4, 29.5, 31.7, 32.8, 34.0, 35.9, 53.8, 68.4, 69.5, 69.7,114.4, 115.8, 119.3, 120.9, 122.1, 126.6, 129.9, 131.9, 132.4, 151.4,155.5, 163.8, 164.1, 164.3, 210.8. m/z (MALDI) 1147.56 (100%) and1149.59 (97%) [M+Na]⁺, C₆₁H₇₃BrNaO₁₁S₂ requires 1147.37 (100.0%) and1149.37 (97%).

4-((3-(4-(4-(Dodecyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl4-(undec-10-enyloxy) benzoate (BC13). Synthesized as described for thepreparation of compound BC1. Quantities: 24 (1.08 g, 2.64 mmol), 18(1.37 g, 2.64 mmol), DMAP (0.32 g, 2.64 mmol), DCC (0.32 g, 5.28 mmol).Yield 1.5 g (62%). EA: Found: C, 74.91; H, 7.30. C₅₇H₆₆0₁₀ requires C,75.14; H, 7.30%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.89 (3 H, t, ³J=6.9Hz, CH₃), 1.24-1.43 (30 H, m, CH₂), 1.84 (4 H, m, O—CH₂—O-CH₂—), 2.04 (2H, m, CH₂—CH═CH₂), 4.06 (4 H, t, ³J=6.5 Hz, O—CH₂), 4.95 (2 H, m,CH═CH₂), 5.80 (1 H, m, CH═CH₂), 6.99 (4 H, d, ³J=8.9 Hz, Ar—H), 7.19 (3H, m, 3H, Ar—H), 7.38 (4 H, d, ³J=8.7 Hz, Ar—H), 7.50 (1 H, t, ³J=8.1Hz, Ar—H), 8.16 (4 H, d, ³J=8.9 Hz, Ar—H), 8.28 (4 H, d, ³J=8.7 Hz,Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.2, 22.7, 26.0, 28.9, 29.1,29.4, 29.45, 29.5, 29.6, 29.65, 29.7, 31.9, 33.8, 68.4, 114.2, 114.4,115.8, 119.3, 121.0, 122.1, 126.6, 129.7, 131.8, 132.4, 139.1, 151.5,155.5, 163.8, 164.0, 164.2. m/z (MALDI) 934.16 [M+Na]⁺, C₅₇H₆₆NaO₁₀requires 933.46.

4-((3-(4-(4-(11-(Acetylthio)undecyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl 4-(dodecyloxy)benzoate (BC14). Synthesized as described for thepreparation of compound BC4. Quantities: BC13 (0.30 g, 0.3 mmol),thioacetic acid (0.2 mL, 2.6 mmol), AIBN (0.05 g, 0.3 mmol). Yield 0.25g (84%). EA: Found: C, 71.44; H, 6.93. C₅₉H₇₀O₁₁S requires C, 71.78; H,7.15%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz): 0.91 (3 H, t, ³J=6.9 Hz, CH₃),1.21-1.66 (36 H, m, CH₂), 1.84 (4 H, m, O—CH₂—CH₂), 2.33 (3 H, s,COCH₃), 2.89 (2 H, t, ³J=7.3, SCH₂), 4.06 (4 H, t, ³J=6.5 Hz, OCH₂),6.99 (4 H, d, ³J=8.9 Hz, Ar—H), 7.22 (3 H, m, Ar—H), 7.40 (4 H, d,³J=8.7 Hz, Ar—H), 7.50 (1 H, t, ³J=8.1 Hz, Ar—H), 8.17 (4 H, d, ³J=8.8Hz, Ar—H), 8.29 (4 H, d, ³J=8.7 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75MHz): 14.5, 14.55, 22.7, 23.1, 26.4, 29.2, 29.5, 29.6, 29.7, 29.75,29.8, 29.9, 30.0, 30.1, 31.0, 32.3, 68.8, 114.8, 116.2, 119.7, 121.3,122.5, 127.0, 130.3, 132.2, 132.8, 151.8, 155.9, 164.2, 164.5, 164.7,196.4. m/z (MALDI) 1009.98 [M+Na]⁺, C₅₉H₇₀NaO₁₁S 1009.45.

4-((3-(4-(4-(Dodecyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl4-(11-mercaptoun-decyloxy)benzoate (BC15). Synthesized as described forthe preparation of compound BC5. Quantities: BC14 (0.16 g, 0.2 mmol), 12M HCl (2 mL). Yield 0.10 g (67%). EA: Found: C, 72.25; H, 7.50.C₅₇H₆₈O₁₀S requires C, 72.43; H, 7.25%. ¹H NMR: δ_(H) (CDCl₃; 300 MHz):0.91 (3 H, t, ³J=6.9 Hz, CH₃), 1.19-1.70 (37 H, m, CH₂/SH), 1.85 (4 H,m, O—CH₂—CH₂), 2.55 (2 H, q, ³J=7.3 Hz, SCH₂), 4.06 (4 H, t, ³J=6.5 Hz,OCH₂), 7.01 (4 H, d, ³J=8.7 Hz, Ar—H), 7.22 (3 H, m, Ar—H), 7.40 (4 H,d, ³J=8.6 Hz, Ar—H), 7.50 (1 H, t, ³J=8.0 Hz, Ar—H), 8.17 (4 H, d,³J=8.7 Hz, Ar—H), 8.29 (4 H, d, ³J=8.5 Hz, Ar—H). ¹³C NMR: δ_(C) (CDCl₃;75 MHz): 14.6, 23.1, 25.1, 26.4, 28.8, 29.5, 29.7, 29.9, 29.95, 30.0,30.05, 30.1, 32.3, 34.4, 68.8, 114.8, 116.2, 119.7, 121.3, 122.2, 122.5,127.0, 130.3, 132.3, 132.75, 132.8, 151.8, 155.9, 164.2, 164.5, 164.7.m/z (MALDI) 967.93 [M+Na]⁺, C₅₇H₆₈NaO₁₀S requires 967.44.

4-((3-(4-(4-(Dodecyloxy)benzoyloxy)benzoyloxy)phenoxy)carbonyl)phenyl4-(10-(ethoxycarbono-thioylthio)decyloxy)benzoate (BC16). Synthesized asdescribed for the preparation of compound BC1. Quantities: 20 (0.21 g,0.4 mmol), 24 (0.18 g, 0.4 mmol), DMAP (0.01 g, 0.09 mmol), DCC (1.12 g,5.4 mmol). Yield 0.15 g (37%). EA: Found: C, 69.52; H, 7.05. C₆₁H₇₄O₁₁S₂requires C, 69.52; H, 6.92%. ¹H NMR: δ_(H)(CDCl₃; 300 MHz): 0.91 (3 H,t, ³J=6.9 Hz, CH₃), 1.24-1.57 (33 H, m, CH₂/O—CH₂—CH₃), 1.67 (2 H, m,S—CH₂—CH₂), 1.85 (4 H, m, O—CH₂—CH₂), 2.88 (2 H, t, ³J=7.4 Hz, SCH₂),4.08 (4 H, t, ³J=6.5 Hz, OCH₂), 4.29 (2 H, q, ³J=7.1 Hz, O—CH₂—CH₃),7.01 (2 H, d, ³J=8.9, Ar—H), 7.21 (3 H, m, Ar—H), 7.40 (4 H, d, ³J=8.7,Ar—H), 7.51 (1 H, t, ³J=8.4, Ar—H), 8.17 (4 H, d, ³J=8.8, Ar—H), 8.30 (4H, d, ³J=8.7, Ar—H). ¹³C NMR: δ_(C) (CDCl₃; 75 MHz): 14.1, 22.7, 26.0,27.0, 29.1, 29.3, 29.35, 29.4, 29.55, 29.6, 29.65, 29.8, 30.9, 31.9,34.0, 63.3, 65.1, 68.4, 68.3, 114.4, 115.8, 119.3, 120.9, 122.1, 126.6,129.9, 131.8, 132.4, 151.4, 155.5, 163.8, 164.1, 164.3, 171.2. m/z(MALDI) 1025.26 [M+Li]⁺, C₅₉H₇₀LiO₁₁S₂ requires 1025.45.

Spectroscopic and calorimetric Measurements

DSC traces acquired on the first round of heating and cooling at a rateof 10° C./min of a) pure BC1, and BC1 doped with b) 2.5 wt % Au1, c) 5wt % Au1, d) 10 wt % Au1, and e) 15 wt % Au1, as well f) pure BC8, andBC8 doped with g) 2.5 wt % Au1, h) 5 wt % Aul, i) 10 wt % Au1, and j) 15wt % Au1.

CONCLUSION

We have presented the synthesis and characterization of a new series ofbent-core molecules functionalized with thioacetate, xanthate or thiolgroups on either only one or both ends. The mono(thiol) functionalizedbent-core derivatives BC10 and BC15 have been successfully attached togold nanoparticles, which display self-assembly behaviour out ofsolution. These particles, if suspended in a

SmCPA host give rise to a number of unique electro-optic effects whichwill be the subject of further studies. The attachment of sulphur-basedfunctional groups to the bent-core LCs could also be used to produceself-assembled monolayers (SAMs) of functional molecules on goldsurfaces.

The invention which has been made, in its product and process aspects isdefined by the following claims.

1. Symetrically substituted bent-core liquid crystal compounds accordingto formula I

wherein m=n=11 and R is —SCOCH₃ or —SH; or m=n=12 and R is —Br or—SCSOEt.
 2. Asymmetrically substituted derivative of bent-core liquidcrystal compounds according to Formula II

wherein m=9, n=10, R₁ is CH₃ and R₂ is SCOCH₃; n=9, n=10, R₁ is CH₃ andR₂ is SH; n=12, n=11, R₁=Br and R₂ =CH₃; m=n=12, R₁ is Br and R₂ isSCSOEt; m=n=11, R₁ is CH₃ and R₂ is SCOCH₃; n=n=11; R₁ is CH₃ and R₂ isSH; or m=11; n=10, R₁ is CH₃ and R₂ is SCSOEt.
 3. A method for preparingbent-core liquid crystal decorated nanoclusters, comprising the steps ofagitating a solution of hexanethiol-capped gold nanoparticles and anassymetrically substituted derivative according to Formula II of claim 2wherein, n=9, n=10, R₁ is CH₃ and R₂ is SH, or wherein n=n=11; R₁ is CH₃and R₂ is SH in an anhydrous volatile solvent, then slowly evaporatingthe solvent under nitrogen and drying the mixture
 4. A method forpreparing bent-core liquid crystal decorated nanoclusters comprising thesteps of: capping gold nanoparticles with a derivative of said firstbent-core liquid crystal compound; suspending said the capped goldnanoparticles in a liquid hydrocarbon; dispersing the capped goldnanoparticles in a derivative of a second bent-core liquid crystalcompound as a host medium to promote the self-assembly of bent-coreliquid crystal decorated gold nanoclusters into arrays.
 5. A methodaccording to claim 4, wherein said derivative of a first bent-coreliquid crystal compound has the Formula I:

wherein m=n=11 and R is —SCOCH₃ or —SH; or m=n=12 and R is —Br or—SCSOEt.
 6. A method according to claim 5, wherein said derivative of asecond bent-core liquid crystal compound according to Formula Ia

wherein n=n=9 and R is —CH₃; or according to Formula IIa

wherein n=9, n=8, R₁ is CH₃ and R₂ is CH=CH₂.
 7. A method for enhancingspontaneous polarization in an SmCPA by dispersing in said SmCPA aselected quantity of bent-core decorated gold nanoclusters prepared bythe method of claim 3 or claim 6.